An official with the Tennessee Department of Transportation said it's still not clear what caused the bridge's concrete railing to come crashing down onto the I-24 merger with I-75 below. However, officials are confident the bridge is structurally sound and will not cause further injuries.

The bridge was inspected in the middle of last year and showed the bridge was structurally fair, according to TDOT regional bridge manager Steve Hutchings. "It had normal problems that an older bridge would have, but there was nothing structurally wrong with it," he said. "There was no reason for us to suspect anything like this would happen. Everything was in good condition."

Observation: When parts of your bridge fall off, even when it's just a concrete guide rail, it hardly wins over public confidence. It actually, is similiar, at least in the piece that fell off, to the bridge in Syracuse.